It is difficult for operators of vehicles such as automobiles, buses, trucks, aircraft, trains and boats to see everything around them, especially objects in their path of travel while driving, flying and piloting. Environmental factors such as the blinding sun or headlights of oncoming or approaching vehicles may interfere with correct visual perception. For example, a red stoplight may be hard to see against the sun and a fighter pilot will lose sight of enemy aircraft as they fly into the sun.
Headlights, especially those incorrectly aimed or left in high beam mode, are a major source of discomfort in night-time driving. Oncoming headlight glare is a major cause of driver fatigue and in some instances, the driver is blinded and left unable to see pedestrians or objects in the vehicle's path. The headlights of following vehicles, especially those installed at higher mounting heights, such as in popular sport utility vehicles, are reflecting at greater intensities off the rearview and side mirrors causing discomfort to many drivers.
There are a number of products and patents on devices to eliminate glare from the sun and headlights from oncoming vehicles. They basically can be broken down into three types. The first type are mechanical shades and filters similar to the present sun visor in which the view of the scene is generally subject to the same blockage or attenuation as is the glare source. The second group attacks the problem from the side of the headlight in addition to the driver by using polarizer on the headlight to align the light for later blockage by a second offset polarizer on the driver's side (see for example, U.S. Pat. No. 3,935,444 to Zechnall, et al. assigned to Robert Bosch G.m.b.H. which describes a polarized light beam source in a vehicle headlight).
A third group to which the invention is primarily directed, uses a light attenuating element only in the specific region of the view from where the glare is observed to be coming from. That is, the driver's view is through a windshield or screen with addressable pixels which when activated, change from light-transmitting to being capable of absorbing light, i.e., light-absorbing. Detectors and a logic control device assess the path of the light rays between the glare source and the driver's eyes and determine the coordinates on the screen through which the rays pass.
An automobile automatic glare reduction method proposed by Faris most recently in International Publication No. WO 02/089714 together with U.S. Pat. No. 5,305,012 uses knowledge of the location of the driver's eyes and the location of the oncoming vehicle's headlights to generate coordinates on a pixelated light valve screen to block glare from the sun and oncoming headlights. Two cameras, one with a view of the environment surrounding the vehicle and one with a view of the passenger compartment, are required. Images obtained from each camera are analyzed to perform pattern recognition for relevant objects. A detailed geometrical analysis is completed each time for the glare source and eye location. These ever-changing spatial locations for multiple light sources and the eyes are used to calculate the blocking point on the pixelated light valve screen. This method suffers from the complexity of using two cameras and the intricacy of computational requirements in a rapidly moving and dynamic environment. A single camera solution is also proposed but it involves locating the camera on the driver's spectacles. This is similar to the Barnes patent (discussed below) and the thought of consumers purchasing no less using such a cumbersome device seems impractical.
U.S. Pat. No. 6,393,133 to Breed et al., also proposes a two camera system using knowledge of the location of the eyes to block glare from the sun and oncoming headlights obtained from an exterior monitoring system. Once again, the key to this technology is the use of trained pattern recognition algorithms and particularly an artificial neural network to recognize the spatial coordinates of the eyes and glare sources and likely involves massive amounts of calculations in a short time frame to sort out the geometries.
There are numerous mechanical and filter material glare shield patents, some with manual and some with automatic positioning, but all will block a general area of the view and not only the glare sources which potentially conceals important information from the driver. A patent which straddles the use of mechanical and electronic sun visors is U.S. Pat. No. 5,714,751 to Chen. Chen describes an automatic visor for continuously repositioning a shading element to shade a target location from the glaring sun. Although an inexpensive detector is now used for the outside glare, this system is only suitable for use with the sun and still uses complex routines to calculate the spatial location of the interior and exterior subjects of interest and the intersection of a ray between them.
British Pat. No. GB 212836 by Nitsche (check the number because a six digit British patent is quite old), U.S. Pat. No. 5,671,035 to Barnes and International Publication No. WO 03/005942 to O'Halloran propose electronic spectacles for use by a driver of a vehicle for minimizing glare from the headlights of an oncoming vehicle. Typically, the spectacles comprise a frame with lenses formed by panels having an electro-optical medium laminated therein. An electronic sunglasses device is also described for selectively reducing the intensity of light in the field of view of an eye. The device can reduce the light intensity emanating from multiple sources. The eye gear has a frame, a power source, a light sensor and two light transmissive lenses having an array of shutter elements. If the light intensity signals exceed threshold values, then one or more elements of the shutter matrices of each lens is darkened.
U.S. Pat. No. 6,244,703 to Resnikoff describes an improved system for calibrating such a device to accommodate differences in facial geometry. Although a single camera/detector system is described, the driver/operator is required to wear a special pair of glasses. This is inconvenient for people who do not wear eyeglasses and are not accustomed to having to wear glasses especially at night and also for people who wear eyeglasses who would have to manage with two apparatus. The need to find and put on and the possibility of misplacement of such a device make it less practical than today's ready-for-use sun visor.
The above patents, though complex, inconvenient and not suitable for installation in consumer-purchased vehicles, have advanced the state of the art and include many of the necessary techniques and algorithms and are included herein by reference.
There are many advantages to be had and numerous applications of anti-glare and other selective field blocking systems making use of the driver's/operator's eye location and gaze. The application below includes some of them and many others are listed in other patents such as those above. All equipment operators of land, air and sea-based vehicles would benefit. A pilot following an aircraft in a dogfight would lose sight of the enemy as he flies into the direction of the sun. An anti-glare system which would allow him to continue visual contact with the enemy aircraft would be highly advantageous. For an automobile alone, there are numerous safety and convenience functions including locating of the eyes of the occupant to permit automatic adjustment of the rear and/or side view mirrors, determining the onset of driver drowsiness, blind spot detection, preventing airbag deployment induced injuries, positioning the driver's seat to place the eyes at the proper position to eliminate the parallax in a heads-up display vision systems, the identification of the occupant for customized settings and security purposes.
Therefore, there exists a need to have a system capable of eliminating glare and maintaining data on the position of the driver's eyes with a minimum amount of components in order to reduce complexity, increase reliability and lower costs.